Websites belonging to the Philippine Anti-Piracy Team, the Department of Environment in Region 3, the Institute for Development and Econometric Analysis, and the Department of Health's Anti-Smoking program were also defaced.

A "Rage Against The Machine" track, "Freedom," played in the background of the hacked websites.

"Anonymous Philippines," in a statement on the websites, said the Cybercrime Prevention Act of 2012 (Republic Act 10175), "is the most notorious act ever witnessed in the cyber-history of the Philippines."

"The Philippine government has just passed a bill that effectively ends the Freedom of expression in the Philippines," the group said.

"The language of the bill is cunningly designed to make you think it only applies to individuals who are deep in cyber-technology and doesn't apply to everyone, but some part of the bill basically says it can imprison anyone who commits libel either by written messages, comments, blogs, or posts in sites such as Facebook, Twitter, or any other comment-spaces of other social media in the Internet," it added.

"New technologies give us new opportunities to connect with a lot of people not only in this country but all over the world. They can also provide us with a medium through which our political, public and even private views can have an immediate and direct impact on individuals, communities and even countries," the group said.

"It is just so disappointing that our government, in adopting our 80-year-old antiquated libel laws to the Cybercrime Law, again seems to have retarded our march with the rest of the world with respect to giving full force to the people's freedom of expression," it said.

Anonymous Philippines said the bill must be revised for the betterment of the Filipino who use the Internet.

"Protect our Right to Freedom of Expression!" the group added.

"No RA can stop an idea. We are Legion. We are ANONYMOUS," one of the hackers said in his Facebook account.

The hacker earlier posted a screenshot of the Twitter feed of one person asking why they remained "quiet" regarding the controversial cybercrime law.

"Challenge accepted!" the hacker later said on Facebook.

Three petitions have been filed before the Supreme Court asking it to strike down several provisions of RA Act 10175, particularly on online libel, the authority given to the Department of Justice to block websites even without a court review, and the warrantless monitoring of electronic data.